(A) MC 3D monoculture without the addition of TGFβ, and (B) in the presence of TGFβ, shown by H&E staining of paraffin-embedded sections. Human collagen type I/III (immunostained with an antibody that recognises both collagen type I and III) (C) and human collagen type IV (D) can be demonstrated in nodules by immunoperoxidase staining. (E) High-power view of MC nodule by scanning electron microscopy in cross section. (F) MC nodule count and collagen type I alpha1 (COL1a1), and collagen type IV alpha1 (COL4a1) RNA quantification (n=3). (G) Effect of ALK5 inhibition (Alk5i) on MC nodule formation (n=3). (H) Effect of SMAD2 or SMAD3 siRNA knockdown in MCs on nodule formation (n=3) with immunoblots demonstrating degree of knockdown. [DharmaFECT (DH), non-targeting siRNA control (siCP), siSMAD2 (siS2), siSMAD3 (siS3), total SMAD2 (tSMAD2), total SMAD3 (tSMAD3)]. Error bars represent 1 s.d. NS, not significant; ***, p<0.001; **, p<0.01: 2-tailed Student’s t test.